Lots of supportive replies to this post, but I'm going to take a different tack - I think you may have pretty badly mis-diagnosed what's going on there.
Firstly, getting more conservative as you get older is normal. And having fewer friends as you get older is normal. There are even jokes about it. You are trying to link the changes in your fathers politics to not having many friends, but you haven't argued why there's a causation vs just being a correlation.
I strongly suspect from your wording that this is because you can't accept that your fathers new politics might have any substance to it. You certainly don't sound like you try to understand why he's angry: you described him as changing from "open minded" (good, positive, liberal) to "recites stuff he heard on TV" (bad, closed minded, conservative). Maybe he feels angry because when he tries to explain how he sees the world and what concerns him, his daughter dismisses him and looks down on him? That'd make any parent kind of upset.
Secondly, you seem to be implying that men over-rely on women for emotional support. Perhaps that's been your experience. As a man, in every relationship I've ever been in, the woman has heavily relied on me for emotional support. This is especially true when in a stable relationship. If anything, girlfriends seem to cause more emotional needs than they solve - a non-trivial amount of emotional support needs that come my way seem to boil down to dramas or blowups between girlfriends.
Finally, I'm not sure men see "no need for a social life" once they get in a relationship. That's a very odd belief. One sad reality is that once a man gets in a stable relationship, women tend to make it hard to sustain relationships with anyone else, whether men or women. This is a pattern I've seen over and over again. I don't think it's really planned or deliberate but it happens. The first to go are obviously any female friends. Many women can't handle their man having close female friends especially if they're single or might become so. But it's pretty common for women to disapprove of male friends too, or to get upset if the man spends too much time out drinking with his buddies instead of spending it with her. The inevitable result is that the man has to pick: friends or girlfriend.
Anyway. If you really want to rebuild your relationship with your father, I suggest a two pronged approach:
1) LISTEN to him when he talks about politics and even engage with him. Don't attack him or make it clear that you feel your own politics are morally and intellectually superior. Ask him why he feels guns are so important, try to see the world from his perspective. If he's always talking about things he heard on TV that implies those are the things that vex and concern him the most. You don't have to agree, but if he feels you're at least trying and can make peace with that, it'll help.
2) Stop trying to find explanations for the way he's changing, especially dubious correlation/causation mixups that boil down to sexist generalisations. People do change as they get older. Moreover the world changes, and young people who have a less fixed identity are often more willing to bend to fit whatever way the wind seems to be blowing. If someone's personality or beliefs don't change with time, that can look to a younger person as if the person's personality has changed when from their perspective it's actually the world that's changing and they stayed the same i.e. what you see as "open mindedness" is in reality just a willingness to accept whatever odd new modern idea comes along, even ideas that seem self-evidently nonsensical to your father.